This application claims priority of DE 199 03 833.3, filed Feb. 1, 1999, in Germany, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an integrated modular collector--heat exchanger unit particularly for a motor vehicle air conditioner, having a collector housing in which a collecting space and a heat exchanger unit with first and second separate heat exchanger ducts in thermal contact with one another, are situated, the first heat exchanger duct having a helical course and being part of a first flow duct which extends from a housing inlet to a housing outlet in the collector housing, and the second heat exchanger duct being part of a second flow duct which extends between the collecting space and a housing connection. Modular units of this type can be used particularly in air conditioners of motor vehicles, such as CO.sub.2 air conditioners, in order to provide in each case a collector and an internal heat exchanger of the refrigerant circulating system in an integrated arrangement.
An integrated modular collector--heat exchanger unit of this type is disclosed in U.S. Pat. No. 3,955,375. The modular unit illustrated there is part of an air conditioner, the collector part of the modular unit being situated between the outlet side of an evaporator and the inlet side of a compressor, and its heat exchanger unit forming an internal heat exchanger between the low-pressure-side refrigerant situated in the collecting space, on the one hand, and the high-pressure-side refrigerant in front of the evaporator inlet side, on the other hand. By way of a lateral inlet in the upper collecting space area, the refrigerant arrives in the collecting space and is sucked out of the latter by way of a top-side collecting space opening. Simultaneously, oil, which has settled in the lower collecting space area, is also sucked out by way of an oil suction tube which extends from there upward out of the collecting space. The integrated modular heat exchanger unit is formed by a coiled tubing arranged in the collector housing and thus in the collecting space, both tube ends on the housing underside extending out of the collecting space and leading there into a laterally provided connection opening of a connection block.
In the case of a modular collector--heat exchanger unit disclosed in German Published Patent Application DE 196 35 454 A1, corresponding to commonly assigned U.S. Patent application Ser. No. 08/915,760, filed Aug. 21, 1997, the heat exchanger unit is formed by one or several flat-tube spirals with mutually spaced turns, the flat tube interior forming a first heat exchanger duct of the heat exchanger unit and the space between the tube spirals forming a second heat exchanger duct of the heat exchanger unit which is in a thermal contact therewith.
From U.S. Pat. No. 4,895,203, a two-fluid heat exchanger is known which is used particularly for the heating of water for industrial use by a coolant of a motor vehicle, which two-fluid heat exchanger has a cylindrical outer housing, a hollow cylinder coaxially arranged in its interior and a fluid-tight coiled tubing which extends between the hollow cylinder and the outer housing and has turns spaced from one another in the axial direction. The coiled tubing forms the heat exchanger duct for the one fluid, while the space between the coil turns acts as a helical heat exchanger duct for the other fluid.
The invention is based on the technical problem of providing an integrated modular collector--heat exchanger unit of the initially mentioned type which has a comparatively simple construction, can be produced at relatively low expenditures and implements a compact integration of the heat exchanger unit in a collector housing with a good heat exchange efficiency.
The invention solves this problem by providing an integrated modular collector--heat exchanger unit, wherein the second heat exchanger duct has a helical course and its coils are in a thermal contact with at least one adjoining coil respectively of the first heat exchanger duct. In the case of this modular unit, characteristically both heat exchanger ducts of the heat exchanger unit have a helical course such that the turns of one duct are in each case in a thermal contact with at least one adjacent turn of the other duct. As a result, the heat exchange media, which separately from one another flow through the two heat exchanger ducts, are in a heat exchange connection with one another along the whole wound duct length. Since, as the result of the coiling, this flow duct length may clearly be larger than the outer dimensions of the heat exchanger unit, the heat exchanger unit with the given required heat exchange capacity can be housed comparatively compactly in the collector housing. Simultaneously, the construction of the heat exchanger unit of two helical heat exchanger ducts, which are in a thermal contact, is relatively simple and can be produced at low expenditures. In particular, it is possible in this case to construct the integrated modular collector--heat exchanger unit as a whole as a pure welded construction without requiring additional soldered connections.
In the case of a modular unit further developed according to preferred embodiments of the invention, the collecting space is formed by a collecting space arranged in the interior of the collector housing, and the heat exchanger unit is implemented in a very simple manner by a coiled tubing which is inserted with axially spaced coils in a sealing manner radially between the interior wall of the collector housing and the exterior wall of the collector housing. While the tube interior of this coiled tubing forms the one heat exchanger duct, the space between the spaced coils of the coiled tubing acts as the other heat exchanger duct. The thus constructed modular collector--heat exchanger unit can be manufactured by means of a few simple components.
In a further development of preferred embodiments of the invention, the collecting tank is open on top, and the pertaining flow duct, which leads from the collecting tank to the exterior housing side, extends from the collecting tank area, which is open on top, by way of the corresponding coiled heat exchanger duct, downward to at least the lower collecting tank area, where it is connected with one or several oil suction bores provided in the collecting tank. In this case, an "oil suction bore" is any fine opening through which a fluid, which is carried along by the actual heat exchanger medium and is clearly more viscous than the latter, is entrained, which fluid may be but does not have to be oil. When used in air conditioners, it is usually lubricating oil for the compressor entrained by the refrigerant. By way of the oil suction bores, this lubricating oil can be entrained again in a controlled manner by the refrigerant sucked from the collecting tank, after it has previously settled on the bottom in the collecting tank.
In a further development according to preferred embodiments of the invention, an increase of the heat exchange capacity is provided in that the exterior wall of the collecting tank has a profiling adapted to the coiled heat exchanger tubing, which results in a heat-exchange-increasing, flat and not only line-shaped contact of the coiled tubing on the exterior wall of the collecting tank. In a further development which also increases the heat exchange, the coiled heat exchanger tubing is provided with an exterior-side surface-enlarging profiling.
In the case of a modular unit further developed according to preferred embodiments of the invention, the heat exchanger unit is formed by a coiled coaxial tubing, in the case of which a radially interior and a radially exterior duct represent the two heat exchanger ducts. This modular unit can also be manufactured in a simple manner and with a few components. In particular, in this case, the collector housing may simultaneously form the boundary of the collecting space, in which the coiled coaxial tubing will then be situated.
In the case of a modular unit further developed according to preferred embodiments of the invention, the two housing-side connection points of the continuous first flow duct, which does not end in the collecting space, are situated on a common housing side, which preferably faces an end area of the coiled heat exchanger ducts, and the flow duct extends by means of a straight tube section in the collector housing to the opposite heat exchanger duct end area. Analogously, as required, the housing-side inlet and outlet for the heat exchange medium to be intermediately stored in the collecting space may also be provided on this housing side so that all connections for the integrated modular collecting--heat exchanger unit are accessible from one side.
In the case of a modular unit further developed according to preferred embodiments of the invention, the coaxial coiled tubing changes in one end area into a U-shaped coaxial tube section which is situated radially within the coil area and by means of which the heat-exchange-effective flow length can be further increased without any enlargement of the modular unit itself.
In a further development of the invention according to preferred embodiments according to the invention, the coaxial coiled tubing is arranged in the collecting space and at one end with its radially exterior duct is shortened such that its mouth end is situated in the upper collecting space area, while the radially interior duct is continued to the exterior side of the housing. In a further development of this measure, the coaxial coiled tubing is provided in a lower collecting space area with one or several oil suction bores which connect its radially exterior duct with the lower collecting space area, in which the more viscous fluid settles which is entrained by the actual heat exchange medium.
In the case of a modular unit further developed according to preferred embodiments of the invention, collecting space feeding devices are provided which feed the heat exchange medium to be intermediately stored in the collecting space to this collecting space by means of a tangential flow component. The resulting rotating inflow current into the collecting space facilitates the desired separation of the actual heat exchange medium and the more viscous fluid entrained by it.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.